【作者】 王艳华；

【导师】 袁峻峰；

【作者基本信息】 上海师范大学 ， 水生生物学， 2004， 硕士

【摘要】 植物抗氧化酶对重金属胁迫的响应以及重金属污染的植物修复已经成为研究的焦点，当前国内外关于铜对植物抗氧化酶影响的研究大多集中于大剂量的急性暴露，对低浓度的慢性效应研究较少。目前国内外对重金属的植物修复方面的研究重点是陆生和挺水超积累植物，对沉水植物的作用很少研究。 本论文以两种大型沉水植物金鱼藻（C.demersum L.）和水盾草（C.caroliniana A.）为受试植物，从它们对水体中Cu²⁺的生物富集作用和动态，以及Cu²⁺对它们体内抗氧化酶的急性毒性效应和亚急性毒性效应两方面进行了研究：1)通过体内暴露不同剂量的Cu²⁺，探讨Cu²⁺对植物体内三种主要的抗氧化物酶（SOD，POD，CAT）的毒理效应，建立剂量—效应关系和时间—效应关系，以揭示沉水植物对Cu²⁺的抗性机制；2)通过对金鱼藻，水盾草单独培养和共同培养的方式，分别研究了两种沉水植物对Cu²⁺的生物富集系数及其动态以及两种植物的种间关系对富集铜和植物耐性的影响，综合评价了两种植物在铜污染水体的植物修复中的应用前景。为沉水植物应用于铜污染的治理提供理论依据。主要研究结果如下： 1．在7天内Cu²⁺对水盾草和金鱼藻CAT，POD，SOD活性的影响存在剂量和时间的阈值。Cu²⁺低浓度和短时间内对抗氧化酶有诱导作用，超过一定的阈限会产生抑制作用；金鱼藻CAT、POD、SOD活性在7天内的最大抑制率与暴露Cu²⁺浓度呈显著正相关。金鱼藻CAT、POD、SOD活性最大抑制率的阈值分别为38.02～46.29％、40.43～87.44％、44.54～49.63％；金鱼藻和水盾草CAT活性在受到Cu²⁺抑制后，一段时间后能够恢复并且表现出强烈的诱导作用；水盾草对Cu²⁺胁迫的耐性比金鱼藻强。水盾草对Cu²⁺的耐受限度在2μmol／L以上，金鱼藻耐受限度在0.2～1μmol／L之间。 2．金鱼藻和水盾草对水体中的铜离子具有一定的生物富集作用。金鱼藻体内富集的铜含量达到137.8mg／kg（干基），符合超级铜积累植物的标准。水盾草体内富集的铜含量可以达到61.0 mg／kg；金鱼藻对铜离子的耐性很低，且叶片受到铜胁迫时容易脱落，不适合作为铜浓度高的水体的生物修复植物，水盾草对铜离子的耐性较高，适合应用于含铜水体的生物修复；金鱼藻和水盾草共同培养时，植物体内对铜的积累量有所增加，金鱼藻对铜的耐性也略有提高。更多还原

【Abstract】 Responses of antioxidant enzyme in plants to heavy metal and phytoremediation of heavy metal are increasingly concerned. At present, many researches concentrated on the effects of copper on antioxidant enzymes have been conducted at home and abroad, most of which were involved in the acute exposure at high dose. But it was rarely studied on the effects dependant on the low exposure concentration and the chronic toxicity to antioxidant enzymes. In the field of the phytoremediation of copper pollution, submerged macrophytes are focused less than the terrestrial plants.In this study, Ceratophyllum demersum L. and Cahomba caroliniana A.Gray were used as the test plant. The following two aspects were investigated in vivo methods: 1) The toxicity effects of Cu2+ on the three main antioxidant enzymes (including CAT, POD and SOD) of two submerged macrophytes were detected at different low doses and on the chronic exposure, in order to establish the dose-effect relationship and the time-effect relationship, and thereby acquire the toxicity threshold; and 2) With two submerge macrophytes throng cultured individual or combined on the chronic exposure, it was found on the BCF of copper and the influence of interspecific relationships to the submerge macrophytes resistance or bioconcentration. The objective in this study was to assess the potential bioremediation feasibility using these two macrophytes in the copper-polluted water. The main results and conclusions were as follows:1. For the acute exposure duration, there expressed the dose-thresholds and time-thresholds in the effects of Cu2+ on the activities of CAT, POD and SOD in two macrophytes. When the test species were exposed at low dose and for a short period, Cu2+ can stimulate activities of antioxidant enzymes. Once exceeding the thresholds, Cu2+ may inhibit enzymes activities. In the seventh day, a significant positive relationship was found between the highest inhibitory ratio of CAT, POD, SOD activity in C. demersum L. and concentrations of Cu2+. The threshold of the highestinhibitory ratio of CAT, POD, SOD in C. demersum L. were respectively 38.02-46.29%, 40.43 - 87.44%, 44.54-49.63%. C. caroliniana A. had a higher tolerance for Cu2+ than C. demersum L. The former could survive at 2 u mol/L Cu2+. but the latter only 0.2- 1 u mol/L.2. C demersum L. and C. caroliniana A. showed certain potential to accumulate Cu2+ in the polluted water. The leaves and stems of C. demersum L. may contain 137.8mg/kg (dry weight) of copper, so it can be served as hyperaccumulators of copper. C. caroliniana A. may contain 61.0 mg/kg of copper; C. demersum L. couldn’t tolerate high lever of Cu2+. Moreover, its leaves tended to rapidly senescence and defoliated in copper treatment group. We suspected that C. demersum L. was inadequate used as a single bioaccumulator. While C. caroliniana A. could tolerate the higher lever of Cu2+, it is advised to be a better selection to phytoremediation. When the two submerge macrophytes were planted together in Cu2+ solution, the respective BCF of copper in two plants increased and the toleration of C. demersum L. was enhanced slightly.更多还原